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MA28155 Dataheets PDF



Part Number MA28155
Manufacturers Dynex
Logo Dynex
Description Radiation Hard Programmable Peripheral Interface
Datasheet MA28155 DatasheetMA28155 Datasheet (PDF)

MA28155 MA28155 Radiation Hard Programmable Peripheral Interface Replaces June 1999 version, DS3575-4.0 DS3575-5.0 January 2000 The MA28155 is a general purpose programmable Input/ Output device designed for use with the MAS281 microprocessor. It has 24 I/O pins which may be individually programmed in 2 groups of 12 and used in 3 major modes of operation. In the first mode (MODE 0), each group of 12 I/O pins may be programmed in sets of 4 to be inputs or outputs. In the second mode (MODE 1), e.

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MA28155 MA28155 Radiation Hard Programmable Peripheral Interface Replaces June 1999 version, DS3575-4.0 DS3575-5.0 January 2000 The MA28155 is a general purpose programmable Input/ Output device designed for use with the MAS281 microprocessor. It has 24 I/O pins which may be individually programmed in 2 groups of 12 and used in 3 major modes of operation. In the first mode (MODE 0), each group of 12 I/O pins may be programmed in sets of 4 to be inputs or outputs. In the second mode (MODE 1), each group may be programmed to have 8 lines of input or output. Of the remaining 4 pins, 3 are used for hand-shaking and interrupt control signals. The third mode of operation (MODE 2) is the bidirectional bus mode, which uses 8 lines for a bidirectional bus and 5 lines, borrowing one from the other group, for hand-shaking. FEATURES s Radiation Hard to 1MRad (Si) s High SEU Immunity, Latch Up Free s Silicon-on-Sapphire Technology s 24 Programmable l/O Pins s All Inputs and Outputs are TTL Compatible s Direct Bit Set/Reset Capability Easing Control Application Interface s Replaces Several MSI Packages s Compatible with MAS281 (Mil-Std-1750A) Microprocessor RD/WN DSN CSN Figure 1: Block Diagram 1/20 MA28155 FUNCTIONAL DESCRIPTION The MA28155 is a programmable peripheral interface (PPI) device designed for use with MAS281. Its function is that of a general purpose l/O component to interface peripheral equipment to the microcomputer system bus. The functional configuration of the MA28155 is programmed by the system software so that, normally, no external logic is necessary to interface peripheral devices or structures. Data Bus Buffer This 3-state, bidirectional, 8-bit buffer is used to interface the MA28155 to the system data bus. Data is transmitted or received by the buffer upon execution of input or output instructions by the CPU. Control words and status information are also transferred through the data bus buffer. Read/Write and Control Logic The function of this block is to manage all of the internal and external transfers of both Data and Control Status words. It accepts inputs from the CPU Address and Control busses and in turn, issues commands to both of the Control Groups. Reset (RESET) A high on this input clears the control register and all ports (A,B,C) are set to the input mode. Chip Select (CSN) A low on this input pin enables the communication between the MA28155 and the CPU. Read/Write Select (RD/WN) A high on RD/WN indicates a CPU read from the MA28155 and a low indicates a CPU data or control word write to the MA28155. The RD/WN line is active only when DSN is low. Data Strobe (DSN) This input indicates that a data transfer is taking place. During a CPU write operation the MA28155 reads data from the bus on the rising edge of DSN. During a read operation the MA28155 outputs data to the bus while DSN is low. Data is valid on the rising edge of DSN. Port Select O and Port Select 1 (AO and A1 ) These input signals, in conjunction with the DSN and RD/ WN inputs, control the selection of one of the three ports of the control word registers. They are normally connected to the least significant bits of the address bus. Basic Operation A1 A0 DSN RD/WN CSN 0 0 1 0 0 1 1 x 1 x 0 1 0 0 1 0 1 x 1 x 0 0 0 0 0 0 0 x 0 1 1 1 1 0 0 0 0 x 1 x 0 0 0 0 0 1 1 1 0 0 READ PORT A → DATA BUS PORT B → DATA BUS PORT C → DATA BUS WRITE DATA BUS → PORT A DATA BUS → PORT B DATA BUS → PORT C DATA BUS → CONTROL DISABLE DATA BUS → TRI-STATE ILLEGAL CONDITION DATA BUS → TRI-STATE Table 1: Basic Operation OPERATIONAL DESCRIPTION Mode Selection There are three basic modes of operation, which can be selected by the system software: Mode 0. Basic Input/Output Mode 1. Strobed Input/Output Mode 2 Bi-directional Bus When the reset input goes high all ports will be set to the input mode (i.e. all 24 lines will be in the high impedance state) After the reset is removed the MA28155 can remain in the input mode with no additional initialisation required. During the execution of the system program any of the other modes may be selected using a single output instruction. This allows a single MA28155 to service a variety of peripheral devices with a single software maintenance routine. The modes for Port A and Port B can be separately defined, while Port C is divided into two portions as required by the Port A and Port B definitions. All of the output registers, including the status register, will be reset whenever the mode is changed. Modes may be combined so that their functional definition can be tailored to almost any l/O structure. For instance; Group B can be programmed in Mode 0 whilst Group A could be simultaneously programmed in Mode 1. 2/20 MA28155 Single Bit Set/Reset Feature Any of the eight bits of Port C can be Set or Reset using a single output instruction. This feature reduces software requirements in control-based applications. When Port C is being used as Status/Control for Port A or B, these bits can be set or reset by.


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